The present invention relates to a suction accumulator for a refrigeration system for separating liquid refrigerant from gaseous refrigerant, for storing the liquid refrigerant and for providing a metered supply of liquid refrigerant to the suction line of a compressor. More specifically, the present invention relates to an improvement in suction accumulators wherein the efficiency of the suction accumulator is increased and the size of the suction accumulator is reduced for a given mass flow rate of refrigerant as compared to prior art suction accumulators. Furthermore, a suction accumulator is provided which is more economical to manufacture than prior art suction accumulators.
Closed loop refrigeration systems conventionally employ a refrigerant which is normally in the gaseous state wherein it may be compressed by means of a compressor. The refrigerant leaves the compressor at relatively high pressure and is then routed through a condenser coil and an evaporator coil back to the compressor for recompression. The refrigerant, after it leaves the evaporator, under some circumstances such as startup of the refrigeration system, may be in its liquid state. Also, during certain operating conditions of the refrigeration system, the evaporator will be flooded and excess liquid refrigerant could enter the suction line and return to the compressor. If liquid refrigerant enters the compressor suction inlet, "slugging" of the compressor may result whereby abnormally high pressures are generated in the compressor which in turn could cause blown gaskets, broken valves, etc.
Accordingly, prior art refrigeration systems have been provided with suction accumulators which act as storage reservoirs for liquid refrigerant which may be present in the suction line to prevent such liquid refrigerant from entering the compressor. Such accumulators permit the liquid refrigerant to change to its gaseous state before entering the compressor. A commonly used type of suction accumulator consists of a liquid storage vessel in which is received a generally U-shaped tube, one end of which is connected to the outlet of the storage vessel and the other end of which is open to the interior of the vessel. As the incoming liquid refrigerant flows into the vessel, it collects in the bottom thereof whereas the gaseous components are carried off through the U-shaped tube and the outlet of the vessel to the compressor suction inlet. Such suction accumulators may also include an orifice located in a bottom portion of the U-shaped tube whereby a small controlled amount of liquid refrigerant is metered into the stream of gaseous refrigerant which flows through the U-shaped tube. Such accumulators may furthermore provide for pressure equalization whereby the pressure at the outlet of the suction accumulator is equalized with the pressure in the liquid storage vessel to prevent higher pressures in the liquid from forcing liquid refrigerant into the suction inlet of the compressor when the compressor is turned off.
A problem with such prior art suction accumulators has been the difficulty in providing a small and compact suction accumulator having a large refrigerant mass flow rate. It is important to provide small suction accumulators, particularly in certain refrigeration systems wherein space is at a premium. Furthermore, it is important that suction accumulators be provided at a reasonable cost. Prior art suction accumulators have generally been made of steel, copper or aluminum parts which are assembled by soldering or brazing and which are therefore expensive both in terms of the cost of materials and labor.
Prior art suction accumulators of relatively small size have been provided, wherein the above-mentioned U-shaped tubes have been integrated into a single conduit including a divider weir or plate to divide the sing1e conduit into two fluid flow passages. These structures have generally also been provided with a metering orifice immersed in the liquid refrigerant. While these types of accumulators represent an improvement over the prior art U-shaped tube type of accumulators, these accumulators have not been as effective as desired in providing a high mass refrigerant flow rate while providing an economical and compact design.
It is therefore desired to provide a compact suction accumulator having an effective liquid metering structure to provide a high refrigerant mass flow rate, while providing an economical design wherein a number of the parts may be molded or extruded from plastic material. It is furthermore desired to provide such an accumulator wherein an effective but simple pressure equalization structure is provided.